KR20220123085A - Method for reactivation of noble metal-iron catalyst and carrying out chemical reaction - Google Patents

Abstract

The catalytic activity of the spent noble metal-iron catalyst is recovered by combining the spent catalyst with an iron(III) compound. This can be done by adding an iron(III) compound to a chemical reaction involving a spent noble metal-iron catalyst. There is no need to add more precious metals. This process is particularly useful in continuous processes for converting nitrogen compounds, such as nitrobenzene, to the corresponding amines.

Description

Method for reactivation of noble metal-iron catalyst and carrying out chemical reaction

The present invention relates to a method for reactivation of a noble metal-iron catalyst, and a chemical reaction using the noble metal-iron catalyst.

Precious metal catalysts are used industrially in various types of chemical manufacturing processes. They are made, for example, by hydrogenation of organic nitrogen compounds such as nitrobenzene to the corresponding amines; hydrogenation of organic aldehydes to the corresponding alcohols; It is used not only to produce hydrogen peroxide through the anthraquinone process, but also in many other applications.

Precious metal catalysts sometimes contain iron, which in some cases improves the performance of the catalyst. See, eg, US Pat. No. 2,823,235, Underhill et al. , Johnson Mathey Technol. Rev. , 2018, 62, (4) 417], Chin et al. , Applied Catalyst A: General 302 (1) 2006 22-31], Kuroki et al. , ACS Appl. Energy Mater. 2018, 1,2, 324-330], and He et al. , J. Hazardous Materials , 164(1), 2009, 126-132].

These catalysts tend to deactivate over time, reducing the reaction rate, especially in continuous processes. In this case, it is necessary to periodically replace the catalyst. Replacing the catalyst is costly.

An alternative to catalyst replacement is to reactivate the catalyst. Various methods have been mentioned to achieve this. U.S. Patent No. 3,959,382 describes a process for reactivating a palladium hydrogenation catalyst by treating an alkali metal or alkaline earth metal compound in a liquid medium. The process described in US Pat. No. 4,999,326 involves contacting a deactivation catalyst with a polar solvent for a naphthalene compound. US 5,143,872 and European EP 1853292 describe contacting a spent catalyst with an aqueous alkaline solution. These methods have little or no effect when applied to noble metal-iron catalysts. See Taninouchi et al. , Metallurgical and Materials Transaction B 49(4) 2918 1781-1793] describes a method for recovering platinum group metals from spent automotive catalytic converters by treatment with FeCl ₂ vapor at a temperature of about 927°C. This forms a recoverable iron-precious metal alloy using magnetic means.

In one aspect, the present invention is a method for reactivating a spent noble metal-iron catalyst. The method comprises combining a waste noble metal-iron catalyst and an iron (III) compound, wherein 10 wt % or less of noble metal based on the weight of iron in the added iron (III) compound is added to the waste noble metal-iron catalyst includes

Applicants have unexpectedly discovered that combining a waste noble metal-iron catalyst with an iron(III) compound can at least partially restore the activity of the waste noble metal-iron catalyst. The iron(III) compound is not an additional amount of noble metal-iron catalyst. Conversely, in this process no or little combination of noble metals with the spent catalyst; The addition of an iron compound alone is sufficient to restore the catalytic action. Therefore, there is no need to add more noble metals in this process, either in the starting form of the noble metal-iron catalyst or in other forms.

Another unexpected advantage is that no special treatment steps are required to increase the catalytic activity as desired. It is sufficient to simply form a physical mixture of the spent noble metal-iron catalyst and the iron(III) compound. Thus, in some embodiments the iron(III) compound may be added directly to a chemical manufacturing process in which the spent noble metal-iron catalyst is present, in which case the spent catalyst is treated separately or (rather than the addition of the iron(III) compound). ) to increase the catalytic activity without the need to change the process conditions in any way.

Accordingly, in a second aspect the present invention is a catalytic process for preparing one or more chemical products, comprising:

a) carrying out a chemical reaction by subjecting one or more starting compounds to reaction conditions in the presence of a noble metal-iron catalyst, wherein the one or more starting compounds react to form one or more chemical products, wherein the reaction is carried out for a period of time continuing at least partially depletion of the noble metal-iron catalyst;

b) thereafter adding the iron(III) compound one or more times to the reaction vessel, after addition of not more than 10% by weight of noble metal, based on the weight of iron in the added iron(III) compound, at least partially spent noble metal- and continuing to carry out a chemical reaction in the presence of an iron catalyst and the added iron (III) compound.

The present invention is of particular significance in continuously operated hydrogenation processes for the production of aromatic amines. In a third aspect, the present invention provides

a) continuously or intermittently introducing a starting nitrogen aromatic compound and hydrogen into a reaction vessel in the presence of a noble metal-iron catalyst, and continuously or intermittently introducing water and an aromatic amine produced by the reaction of the starting nitrogen aromatic compound with the hydrogen from the reaction vessel or intermittently removing to perform a continuous reduction reaction, wherein the reduction reaction is continued for a certain period of time so that the noble metal-iron catalyst is at least partially consumed;

b) thereafter adding an iron(III) compound one or more times to the reaction vessel, after addition of no more than 10% by weight of noble metal based on the weight of iron in the added iron(III) compound, at least partially spent noble metal - It is a process comprising the step of continuously carrying out a continuous reduction reaction in the presence of an iron catalyst and an iron (III) compound.

The noble metal-iron catalyst is a composition containing at least one noble metal and iron. By "precious metal" is meant gold, silver, ruthenium, rhodium, palladium, osmium, iridium and platinum. Among these, palladium and/or platinum are preferred.

The noble metal and iron in the catalyst may exist as an alloy of each other in the form of metals, or in the form of salts, oxides or other compounds. Precious metals and iron can be deposited together on a support. Such a support may be a fixed bed type of support or a particulate support. The support may be any material that is inert under the reaction conditions. Examples of useful support materials include zeolites, molecular sieves, titanium dioxide, alumina, silica, other metal oxides and/or nitrides, and various forms including carbon black, activated carbon (including activated carbon and activated coke), graphite, activated carbon, and the like. contains carbon. Activated carbon is microporous carbon having a porosity of at least 3000 m ² /g as measured by a gas deposition method.

The supported fresh catalyst may contain from 1% to 25% by weight of noble metals and from 1% to 25% by weight iron, based on the total weight of the supported catalyst on a dry basis. In some embodiments, the weight of noble metal and iron comprises at least 2%, at least 3%, or at least 4%, and at most 20%, at most 15%, at most 10%, or at most 7.5% of the total dry weight of the fresh supported catalyst, respectively. make up By "new" catalyst is meant a catalyst that has never been used before.

In a specific embodiment, the catalyst is present in fresh state, in each case from 2% to 10% by weight, in particular from 3% to 7.5% by weight, of palladium and/or platinum and equal amounts, based on the total dry weight of the fresh catalyst supported. carbon-supported palladium-iron or palladium-platinum-iron catalysts containing iron of

Methods for preparing noble metal-iron catalysts are described, for example, in US Pat. No. 2,823,235, Berry et al. , Applied Catalysis A: General 204(2) 2000 191-201, Underhill et al. , Johnson Mathey Technol. Rev. , 2018, 62, (4) 417], He et al. , J. Hazardous Materials , 164(1), 2009, 126-132], Chin et al. , Applied catalyst A: General 302 (1) 2006 22-31], Kuroki et al. , ACS Appl. Energy Mater. 2018, 1,2, 324-330]. Catalysts prepared according to any of these methods are suitable for use in the present invention.

Noble metal-iron catalysts are used to carry out chemical reactions. In a chemical reaction, one or more starting compounds are subjected to reaction conditions including the presence of a catalyst, wherein the one or more starting compounds react to form one or more chemical products.

The chemical reaction may include, for example, an oxidation reaction such as oxidation of phenol to form hydrogen peroxide, or oxidation of carbon monoxide; dechlorination or dehydrochlorination reaction; hydrodeoxygenation reaction; reduction reaction; hydrogenation reaction; or any other reaction in which noble metal-iron catalysts are useful.

In some embodiments, the chemical reaction is the reduction (hydrogenation) of a nitrogen compound to the corresponding amine. The nitrogen compound may be a nitrogen group or a nitrogen aromatic compound in which nitrogen groups are directly bonded to carbon atoms of an aromatic ring. In certain embodiments, the nitrogen compound is nitrobenzene and the resulting amine is aniline.

The chemical reaction was carried out in the presence of a noble metal-iron catalyst for a period of time, such that the noble metal-iron catalyst was at least partially consumed. In a chemical reaction, the catalyst is considered to be at least partially consumed during or after use, and in the presence of the noble metal-iron catalyst itself (i.e. without the addition of an iron(III) compound) a decrease in the rate of the chemical reaction is When present, the catalyst shows a decrease in activity. The decrease in activity can be measured in situ by periodically measuring the reaction rate, or by recovering all or part of the catalyst and measuring the activity by an appropriate test.

Applicants have discovered that metals, particularly iron, in the catalyst can be depleted during use. Thus, the metal content, in particular the iron content, of the catalyst differs from that of the fresh catalyst during use. Changes in metal content, particularly iron depletion, are believed to reduce the reaction rate, at least in part, by lowering the catalytic activity. Thus, a catalyst is considered to be at least partially consumed if all or part of the iron content at the start (ie the iron content in the catalyst prior to use) is lost.

In the present invention, iron is replenished at least partially by combining a spent noble metal-iron catalyst with an iron(III) compound. This is done while up to 10% by weight of noble metal, based on the weight of iron in the added iron(III) compound, is added to the spent noble metal-iron catalyst. Preferably, any noble metal added during this combining step is added to the iron(III) compound at a maximum impurity level, such as 500 ppm or less, 100 ppm or less, or 10 ppm or less by weight based on the weight of iron. do. In some embodiments, the noble metal is not added with the iron(III) compound, so the total amount of noble metal in the combination is provided by the spent noble metal-iron compound.

Additional noble metals can be added in the form of new noble metal-iron catalysts, if any.

The iron(III) compound may be, for example, an iron(III) halide, such as iron(III) fluoride, iron(III) chloride, iron(III) bromide and the like; iron(III) nitrate, iron(III) phosphate; iron (III) pyrophosphate, iron oxide (Fe ₂ O ₃ ); basic iron(III) carbonate, iron(III) carbonate, ferric hydroxide, iron(III) alkoxide; iron(III) aryloxides such as iron phenoxide; iron(III) carboxylate; iron(III) salicylate; iron(III) 3,5-di-t-butyl salicylate; iron(III) acetylacetonate; and iron(III) t-butylacetylacetonate. In some cases, where external organic species are avoided to enter the reaction, inorganic iron(III) compounds are preferred.

In some embodiments, the iron(III) compound may be a solid, insoluble under the conditions of the chemical reaction employed, and non-reactive in the reaction mixture except for catalysis. The solid and/or supported iron(III) compound may be in physical form, for example as a catalyst bed or catalyst particles. When in particulate form, the longest dimension of the solid and/or supported iron(III) compound (including the support, if any) may be between 10 nm and 10 mm, or between 25 nm and 100 μm.

The iron(III) compound may be carried on a support as described above with respect to noble metal-iron catalysts.

Particularly suitable for reduction and/or hydrogenation reactions, such as the reduction of organic nitrogen compounds to the corresponding amines (in particular hydrogenation of nitrogenaromatic compounds such as nitrobenzene to aromatic amines such as aniline), iron(III) compounds are hydroxy acid Ferric ferric or iron oxide, which may be carried on an inorganic support, in particular the carbon support described above (eg activated carbon support).

The spent noble metal-iron catalyst and iron(III) compound can be combined by simply mixing the materials to form a physical mixture. In general, there is no need to treat the physical mixture in any particular way, such as to promote or cause chemical reactions, fusions, alloys, or otherwise marry the starting materials. It has been found that these physical mixtures are often as catalytically active as new noble metal-iron catalysts.

Mixing may be carried out, for example, by recovering all or part of the at least partially spent noble metal-iron catalyst from the chemical reaction, and combining the recovered noble metal-iron catalyst with the iron(III) compound to form a physical mixture. can The physical mixture thus obtained can be reintroduced into the chemical reaction of interest. By “recovering” it is meant that the catalyst is at least partially separated from the reactants of the chemical reaction. This can be done, for example, by removing the spent catalyst from the reaction vessel, removing the reactants from the reaction vessel and leaving the spent catalyst in the reaction vessel, or withdrawing a recycle stream containing all or part of the catalyst from the reaction vessel. . Recycling of the spent catalyst, such as forming a mixture of the iron(III) compound recovered from the reaction vessel and the spent catalyst, and reintroducing the resulting mixture into the reaction vessel, is not considered to have added precious metals for the purposes of the present invention.

An unexpected advantage of the present invention is that the spent catalyst does not have to be recovered from the chemical reaction. By combining this with an iron(III) compound in the presence of a reactant, a mixture of the spent catalyst and the iron(III) compound can be formed in situ even if the chemical reaction proceeds. In this embodiment, the iron(III) compound can simply be introduced into the reaction vessel as the reaction proceeds in the presence of the spent catalyst, and the chemical reaction is then carried out when both the spent catalyst and the iron(III) compound are present.

In general, a mixture of at least partially consumed noble metal-iron catalyst and iron(III) compound is introduced into a chemical reaction when the starting noble metal-iron catalyst is at least partially consumed. If desired, any analytical method suitable for a particular chemical reaction may be used to monitor the decrease in catalytic activity and thus the decrease in the rate of the reaction. For example, the conversion rate of one or more starting materials can be determined, wherein a lower conversion rate indicates a greater loss of catalytic activity and a reduced reaction rate. Similarly, the rate of consumption of one or more starting materials can be measured, wherein a decrease in the rate of consumption is in turn indicative of a decrease in catalytic activity and rate of reaction. The concentration and/or rate of one or more products of a chemical reaction can be measured as an indicator of a decrease in catalytic activity and reaction rate. If desired, samples of the noble metal-iron catalyst can be recovered from the chemical reaction to analyze iron content or to evaluate catalysis.

Instead of or in addition to monitoring the chemical reaction, a general rate of decline in catalytic activity can be established empirically for any particular chemical reaction under a particular set of operating conditions. Thereafter, the iron(III) compound should be provided to the reaction vessel using empirical data to estimate at least one time when the catalyst activity and reaction rate will decrease. Using empirical data in this way, it is possible to establish a schedule for feeding the iron(III) compound to the reaction. In this case, the iron(III) compound may be added intermittently or continuously to maintain the desired catalytic activity and reaction rate.

The chemical reaction then continues in the presence of both the spent noble metal-iron catalyst and the iron(III) compound.

The present invention is useful in a continuous process. In such a continuous process, one or more starting materials are continuously or intermittently introduced into the reaction vessel in the presence of a noble metal-iron catalyst, and one or more reaction products are continuously or intermittently removed from the reaction vessel. When the noble metal-iron catalyst is partially or wholly consumed, the catalytic activity and chemical reaction rate are increased by continuously or intermittently adding an iron(III) compound to the reaction vessel during continuous operation. The chemical reaction is then continued in the presence of partially or wholly consumed noble metal-iron catalyst and iron(III) compound.

In certain embodiments, the chemical reaction is the reaction of a starting nitrogen aromatic compound with hydrogen to produce the corresponding aromatic amine. If the nitrogenaromatic compound is nitrobenzene, the amine product will be aniline.

In a useful continuous process for the production of aniline according to the present invention, nitrobenzene and hydrogen are intermittently or introduced successively. The internal pressure of the reaction vessel may be, for example, a gauge of 10 to 30 atmospheres (1013 to 3040 kPa). Nitrobenzene and hydrogen are reacted in the presence of a noble metal-iron catalyst in a reaction vessel to produce aniline and water. Aniline and water are continuously or intermittently removed in the gas phase at the top of the reaction vessel to purify the aniline. The reaction continues for a period of time until the noble metal-iron catalyst is at least partially consumed. The iron(III) compound is added intermittently or periodically to the reaction vessel during the continuous process, and the reaction is carried out after addition of the iron(III) compound in the presence of at least partially consumed noble metal-iron catalyst and iron(III) compound. continues in courage.

In a continuous process, a convenient way to add the iron(III) compound is to withdraw a recycle stream containing the spent noble metal-iron catalyst from the reaction vessel, and in all or part of the recycle stream, the spent noble metal-iron catalyst and the iron(III) compound after combining, a corresponding portion of the recycle stream containing the spent noble metal-iron catalyst is reintroduced, and the iron(III) compound is added to the reaction vessel. This can be done intermittently or continuously. The recycle stream typically contains a liquid phase, which may include, for example, some amount of unreacted starting material, solvent and/or product. Some or all of the liquid phase may be removed from the recycling stream before the recycling stream is reintroduced into the reaction vessel. For example, product may be recovered from the recycle stream before the recycle stream is reintroduced into the reaction vessel. For nitrogenaromatic hydrogenation, the recycle stream may contain some amount of product aromatic amine (aniline for nitrobenzene hydrogenation). Some or all of the aromatic amine may be recovered from the recycle stream before the recycle stream is reintroduced into the reaction vessel.

The following examples are provided to illustrate the present invention, but are not intended to limit its scope. All parts and percentages are by weight unless otherwise specified. All molecular weights are number averages unless otherwise specified.

Examples 1 to 4 and Comparative Samples A and B

Reaction time experiments are carried out in the following approximate manner: 0.027 g to 0.028 g of palladium-iron catalyst described below in a 300 mL autoclave (Autoclave Engineers Model ABA-300, steam-jacketed and equipped with a stirrer). , 17.2 mL of nitrobenzene, 30 mL of methanol and 50 mL of water. The reactor is sealed, purged with hydrogen and pressurized with nitrogen to a gauge pressure of 30 bar (3,040 kPa). Steam flows through the jacket to heat the reactor contents to 100°C. The time at which the reactor contents reach 100° C. is designated as time T ₀ . The pressure in the reactor is continuously measured. Determine the point at which the pressure becomes constant (T _c , indicating the end of the reaction). The reaction time is calculated as T _c -T ₀ .

In Comparative Sample A, the palladium-iron catalyst is a fresh catalyst sample containing about 4.6 wt% palladium, 0.4 wt% platinum, and 5.15 wt% iron (all inductively-coupled plasma-mass based on dry weight). determined by spectroscopy (ICP-MS)). The metal is transported on the carbonaceous support particles. The palladium-iron catalyst is prepared according to the method described in US Pat. No. 2,823,235.

For Comparative Sample B, the palladium-iron catalyst was obtained from a commercial aniline production plant as a waste sample of the same palladium-iron catalyst.

The reaction times of Comparative Samples A and B were 7.1 to 7.2 minutes and 19.3 to 19.7 minutes. Thus, the activity of the spent catalyst in this test is about one-third that of the fresh catalyst.

ICP-MS analysis of the spent catalyst revealed that the levels of palladium and platinum in the spent catalyst were little different from those of the fresh catalyst. However, it was found that the iron content of the spent catalyst was reduced by about 60%, ie to about 2.1% by weight of the catalyst.

Comparative sample B is repeated four more times, in each case ferric chloride (FeCl ₃ .6H ₂ O) is added as a physical mixture with the spent catalyst. In Example 1, ferric chloride is added sufficient to provide 1 part by weight iron per 100 parts by weight spent catalyst. In Examples 2 to 4, ferric chloride is added to provide 2, 3 or 4 parts by weight of iron per 100 parts by weight of spent catalyst. Approximate total amounts of iron (including iron from spent catalyst and ferric chloride) and reaction times are given in Table 1 together with the results of Comparative Samples A and B.

[Table 1]

As shown in the data in Table 1, the addition of ferric chloride to the reaction significantly reduces the reaction time compared to the spent catalyst. If the iron content in the reaction mixture is increased approximately by the iron content of the fresh catalyst, the reaction time is essentially the same but not faster than providing fresh catalyst. Smaller amounts of iron(III) compounds added, even smaller, give important advantages.

Example 5 and Comparative Sample C

Although the addition of ferric chloride to the nitrobenzene reduction reaction described in the previous examples greatly improves the reaction rate, the presence of chloride ions results in the formation of unwanted by-products in certain reactions. Accordingly, for the reduction of nitrogen compounds to the corresponding amines, iron(III) compounds with little, if any, halide ions are preferred.

Ferric chloride and activated carbon were combined in the presence of water in a weight ratio of iron to carbon of 1:20. Sodium bicarbonate is added, which reacts with ferric chloride to form basic ferric carbonate, which precipitates with activated carbon and sodium chloride. The iron carbonate-activated carbon particles are separated from the liquid phase and heated to 80° C. for 30 minutes to decompose the iron carbonate to ferric hydroxide. Thereafter, the particles are washed, filtered and dried.

Comparative Sample C is performed according to the general reaction time procedure described above. The catalyst was a spent palladium-iron catalyst from a commercial aniline production facility, originally prepared according to the method described in US Pat. No. 2,823,235.

In Example 5, a mixture of the same spent catalyst and ferric hydroxide-activated carbon particles was used. The mixture is formed by separately adding spent catalyst and ferric hydroxide-activated carbon particles to a reactor. The ferric hydroxide-activated carbon particles are sufficiently added to supply iron in an amount of about 4 wt-% based on the weight of the spent catalyst particles. The total iron content in the combined spent catalyst and ferric hydroxide-activated carbon particles is 5 to 6.25% by weight of the spent catalyst particles. The results are shown in Table 2 together with the results of Comparative Sample A.

[Table 2]

As demonstrated in the data in Table 2, addition of iron in the form of iron hydroxide supported on activated carbon restores the catalytic activity to approximately that of the fresh catalyst. No form of unwanted reaction by-products.

Claims (15)

A method for reactivating a spent noble metal-iron catalyst, wherein the waste noble metal-iron catalyst and an iron (III) compound are combined, wherein 10 wt% or less of the noble metal is waste based on the weight of iron in the added iron (III) compound. adding to the noble metal-iron catalyst. The method of claim 1 , wherein the iron(III) compound is inorganic. 3. The method of claim 2, wherein the iron(III) compound is iron(III) halide, iron oxide, basic iron(III) carbonate, iron(III) carbonate, or iron(III) hydroxide. 4. The method according to any one of claims 1 to 3, wherein the noble metal is palladium, platinum, or a mixture of palladium and platinum. 5. The method according to any one of claims 1 to 4, wherein the noble metal-iron catalyst is supported on a carbonaceous support. A catalytic process for preparing one or more chemical products, comprising:
a) carrying out a chemical reaction by subjecting one or more starting compounds to reaction conditions in the presence of a noble metal-iron catalyst, wherein the one or more starting compounds react to form one or more chemical products, wherein the reaction is carried out for a period of time continuing at least partially depletion of the noble metal-iron catalyst;
b) thereafter adding the iron(III) compound one or more times to the reaction vessel, after addition of not more than 10% by weight of noble metal, based on the weight of iron in the added iron(III) compound, at least partially spent noble metal- A catalytic process comprising continuously conducting a chemical reaction in the presence of an iron catalyst and the added iron(III) compound. 7. The catalytic process according to claim 6, wherein the iron(III) compound is inorganic. The catalytic process according to claim 7 , wherein the iron(III) compound is iron(III) halide, iron oxide, basic iron(III) carbonate, iron(III) carbonate, or iron(III) hydroxide. 9. The catalytic process according to any one of claims 6 to 8, wherein the noble metal is palladium, platinum, or a mixture of palladium and platinum. 10. The catalytic process according to any one of claims 6 to 9, wherein the noble metal-iron catalyst is supported on a carbonaceous support. 20. The method according to any one of claims 6 to 19, wherein the chemical reaction is an oxidation reaction, dechlorination or dehydrochlorination reaction; hydrodeoxidation reaction; at least one of a reduction reaction or a hydrogenation reaction. A process for the preparation of aromatic amines, comprising:
a) continuously or intermittently introducing a starting nitrogen aromatic compound and hydrogen into a reaction vessel in the presence of a noble metal-iron catalyst, and continuously or intermittently introducing water and an aromatic amine produced by the reaction of the starting nitrogen aromatic compound with the hydrogen from the reaction vessel or intermittently removing to perform a continuous reduction reaction, wherein the reduction reaction is continued for a certain period of time so that the noble metal-iron catalyst is at least partially consumed;
b) thereafter adding an iron(III) compound one or more times to the reaction vessel, after addition of no more than 10% by weight of noble metal based on the weight of iron in the added iron(III) compound, at least partially spent noble metal - continuously carrying out a continuous reduction reaction in the presence of an iron catalyst and an iron (III) compound. The process according to claim 12 , wherein the iron(III) compound is iron(III) halide, iron oxide, basic iron(III) carbonate, iron(III) carbonate, or iron(III) hydroxide. 14. The process according to claim 12 or 13, wherein the noble metal is palladium, platinum, or a mixture of palladium and platinum. 15. The process according to any one of claims 12 to 14, wherein the noble metal-iron catalyst is supported on a carbonaceous support.